The present invention relates to organopolysiloxane compositions which are curable in the presence of a precious metal containing catalyst by reaction of .tbd.SiH groups with silicon-bonded olefinically unsaturated groups. More particularly, the present invention relates to novel inhibitors for such addition curable organopolysiloxane compositions which permit the ingredients to be combined for considerable lengths of time without curing.
Silicone compositions which are curable by reaction of .tbd.SiH groups with silicon-bonded olefinic groups in the presence of a hydrosilation catalyst are well known in the art, for example, as described in U.S. Pat. Nos. 2,823,218; 3,249,581 and 3,436,366, all of which are incorporated by reference into the present disclosure. Because curing begins upon mixing of the aforesaid ingredients, it is the usual practice to provide addition curable compositions in two packages, one of which contains the olefinically unsaturated polysiloxane and the hydrosilation catalyst, and the other the organohydrogenpolysiloxane crosslinking agent.
When it is necessary to extend the the pot life of addition curable organopolysiloxane compositions or provide one-component addition curable organopolysiloxane composition, a cure inhibitor can be included therein. Generally, cure inhibitors are compounds which slow curing at ambient temperatures but do not retard curing at elevated temperatures. Examples of inhibited, precious metal catalyzed organopolysiloxane compositions can be found in U.S. Pat. Nos. 3,188,299 (dialkyl formamides, thioamides, alkyl thioureas); 3,188,300 (organophosphorous); 3,192,181 (benzotriazoles); 3,344,111 (nitriles); 3,445,420 (acetylenic alcohols); 3,453,233 (tris-triorganosilyl amines); 3,461,185 (tetramethylguanidine carboxylates); 3,723,567 (aminoalkylalkoxysilanes); 3,882,083 (isocyanurates); 4,043,977 (diaziridines); 4,239,867 (higher alkyl amines); 4,256,870 (dialkyl maleic esters); and 4,347,346 (dialkylacetylene dicarboxylates).